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Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATION

The effect of evidence timing and witness motivation upon juror

evaluations of alibi witnesses and defendants

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONAbstract

The present study examined whether evidence timing and witness motivation

effect mock jurors’ decisions. Participants read a mock case where the

defendant’s alibi was; not corroborated, corroborated by a motivated alibi

witness (with prior relationship with the defendant), or corroborated by an

unmotivated alibi witness (with no relationship with the defendant). Where

present, the alibi corroboration was provided either at a timely point in the police

investigation, or delayed to ‘ambush’ the court. Supporting prior literature,

timely alibis were seen as significantly more reliable when substantiated by an

unmotivated alibi witness than by a motivated witness. Additionally, when the

alibi witness was unmotivated, timely evidence was perceived as significantly

more reliable than ambush evidence. However, alibi corroborator and timing did

not have a significant effect on either case verdicts or perceptions of defendant

reliability. The findings suggest that defendants may not be unfairly advantaged

if their ambush alibi is admitted into court.

Keywords: alibi witness evidence; alibi timing; alibi witness motivation;

juror decision-making; credibility; deception; juror decision-making; mock juries;

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONAlibi timing and alibi witness motivation

Considerable research has focused upon prosecution eyewitnesses (see

for example Bradfield Douglass, Neuschatz, Imrich, & Wilkinson, 2010) whereas

research and understanding of alibi evaluations remains limited (Sommers &

Douglass, 2007). It has been demonstrated in real cases in America that alibi

corroboration from friends, family, and/or acquaintances does not always

prevent false convictions (The Innocence Project, 2010), possibly because alibi

evidence is perceived as being less reliable than other forms of trial evidence,

such as DNA and eyewitness testimony (Olson & Wells, 2004). In fact, alibis

appear be viewed negatively as a default (Allison, Jung, Sweeney, & Culhane,

2014) with the high level of suspicion directed towards alibi evidence dubbed

the alibi scepticism hypothesis (Olson & Wells, 2004). In addition, people

perform at worse than chance levels when discriminating between true and

false alibi statements (Culhane, et al., 2013). It is therefore likely that juror

biases and poor detection of deceptive alibis are hindering the administration of

justice (Wells et al., 1998). Further research is required if this type of evidence

is to be better understood and evaluated more accurately in court.

Motivation

The alibi literature has drawn a distinction between motivated alibi

witnesses (with an existing relationship with the defendant) and unmotivated

alibi witnesses (with no relationship with the defendant prior to the case), based

upon the alibi witness’s perceived motivation to lie for the defendant. Culhane,

Hosch, and Kehn (2008) found that a majority of participants believed someone,

mostly a friend, parent or romantic partner, would lie on their behalf if required.

More recently, Culhane et al. (2013) discovered that alibis provided by student

participants were most commonly corroborated by family, friends and familiar

others, with strangers and colleagues rarely providing a supporting statement.

Furthermore, Hosch, Culhane, Jolly, Chavez, & Shaw (2011) found that

participants were most willing to lie for their biological relations (sister and

cousin), followed by those related by marriage (sister-in-law and cousin-in-law)

and were least likely to lie for individuals with only a social connection (co-

worker and stranger seen regularly in a shop). Similarly, a significant

association between unmotivated alibi witnesses and revealing a defendant’s

offending behaviour has also been found when utilising a more ecologically

valid mock-police interview paradigm (Fawcett, 2012) rather than

questionnaires (Culhane, et al., 2008; Hosch et al., 2011). In general, the

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONevidence suggests a greater likelihood of deception by motivated compared to

unmotivated alibi witnesses.

Prior research has posited that motivated alibi witness deception stems

from increased likelihood of reciprocal altruism amongst known individuals

(Hosch et al., 2011). Hosch et al. suggest that Hamiliton’s (1964) kin selection

theory could explain why individuals are more willing to provide a false alibi for

those to whom they are genetically related; the altruistic false alibi enhances the

chance of shared genes being based to future generations. Greater alibi

scepticism towards defendants with motivated alibi witnesses compared to

those with an unmotivated alibi witness or no alibi witness at all (Burke & Turtle,

2004; Culhane, 2005; Culhane & Hosch, 2004; Golding, Stewart, Yozwiak,

Djadali, & Sanchez, 2000) could also be explained by evaluator decision-

making being driven by a belief in kin selection theory and/or reciprocal

altruism.

As individuals spend the majority of their time with family members and

friends it is only logical that these relations are the most common individuals

cited to corroborate genuine alibis both experimental research (Culhane et al.,

2013) and real life settings. However, Olson and Wells (2004) discovered that

participants overestimated the ease with which alibi providers can produce

strong evidence to support their alibi, suggesting that alibi scepticism stems

from the misperception that genuine alibis are easy to strongly corroborate. On

a positive note, once they realised the difficultly of constructing their own alibi,

participants subsequently viewed others' alibis more leniently. This implies that

there may be a simple solution to counteract alibi scepticism; getting jurors to

experience for themselves the difficulty of alibi generation and corroboration.

However, more recently Strange, Dysart, and Loftus (2014) found that

generation of their own alibi did not make people more trusting towards alibi

witnesses.

Another aspect of alibi scepticism is the belief that unmotivated strangers

are more likely to provide accurate alibis as they have no clear motive to lie.

However, Marion and Burke (2013) found that 23% of participants lied to protect

a previously unknown individual accused of a mock theft, showing that relative

strangers cannot always be relied upon to be honest. Furthermore, individuals

do not appear to consider the possibility of unmotivated stranger alibi witnesses

being unreliable due to mistaken identification of the defendant (Olson & Wells,

2004). Therefore, just as people have an inaccurate understanding of the

factors that influence prosecution eyewitness accuracy (Neal, Christiansen,

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONBornstein, & Robicheaux, 2012) it appears they are also unaware of the factors

which could affect alibi witness accuracy. Despite some evidence that

motivation of child alibi witnesses does not influence perceptions of defendant

guilt (Price & Dahl, 2012), there is almost blanket scepticism of motivated adult

alibi witnesses (Olson & Wells, 2004). However, the evidence presented here

suggests that this scepticism may be misplaced. This highlights the need for

further academic attention on this issue, given the limited existing research.

Alibi timing

In accordance with section 6A(2) of the Criminal Procedure and Investigations

Act (1996) in England and Wales the defence must give details of their defence

statement if an alibi is involved. This allows thorough police investigation to

exonerate innocent suspects with robust alibis prior to trial (Lord Chief Justice of

England and Wales, 2008), therefore saving the time and money associated

with a lengthy court case (Epstein, 1964). The very fact that the defendant is in

court despite having an alibi may imply to jurors that the alibi is unreliable or

false. It is, therefore, no surprise that mock detectives consider alibis to be

stronger than do mock jurors (Sommers & Douglass, 2007). In relation to this

Gooderson (1977) points out that the term alibi is heavily loaded and rather than

being another piece of trial evidence, an alibi is viewed as a point for the

defence to prove. In fact, alibis are only considered by jurors when there is a

lack of other strong evidence in the case and prevent police scrutiny of their

alibi veracity (Shpurik & Meissner, 2004). It may, therefore, be in the interests

of defendants with a weak or false alibi to withhold this from the prosecution

team until trial in order to ambush the case. Kerans (1982) states that "without

notice of it [the alibi], the Crown is surprised and cannot rebut without an

adjournment to investigate" (p. 47). Thus, there is a clear incentive for guilty

defendants or those with little or no corroborating evidence to provide an

ambush (deliberately delayed) alibi.

Through ruling as inadmissible any evidence that has not been disclosed prior

to trial, judges have the ability to prevent alibis ambushing cases (R v Chorley

Justices 2006). However, Epstein (1964) found that 52% of American

prosecutors surveyed stated that alibi evidence not disclosed at an early stage

was never or seldom excluded from court. More recently, an analysis of

Canadian cases demonstrated that ambush alibis were a common tactic despite

most Canadian jurisdictions having an early disclosure requirement similar to

that in England and Wales (Criminal Justice Act, 2003; Criminal Procedure and

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONInvestigations Act, 1996; Turtle & Burke, 2003). In fact, the Lord Chief Justice

of England and Wales (2008) stated that he could not think of a single instance

where a lack of disclosure prevented an alibi defence being heard in court, such

was the rarity of this ruling being followed. This apparent international disregard

of legislation and case law may be due to the overriding objective of the criminal

procedure rules for criminal cases to be dealt with 'justly.’ A judge's refusal to

admit potentially exonerating evidence into court solely due to its late disclosure

may not be considered just. The potential therefore exists for ambush alibis to

weaken the prosecution team's case and ultimately allow guilty defendants to

be acquitted.

However, several American studies demonstrate that ambush alibis may not

provide defendants with an unfair advantage in court. Utilising a mock juror

research paradigm Berman and Cutler (1996) revealed that convictions were

less likely in the presence of any inconsistent prosecution eyewitness testimony.

Furthermore, witnesses whose statements in court are inconsistent with their

previous statements are perceived as being significantly less accurate than

witnesses who exaggerate, are inconsistent with other witnesses or recall items

not previously recalled (Brewer, Potter, Fisher, Bond, & Luszcz, 1999).

Similarly, American police officers’ responses to questionnaires demonstrate

that changes to alibis are generally thought to be indicative of deception, rather

than memory failures (Dysart & Strange, 2012), and these changes are

evaluated more negatively than alibis than are maintained (Culhane & Hosch,

2012). This may be due to evidence inconsistency being a popular, although

inaccurate, cue to deception (Vrij, 2008). Confidence is greater amongst alibi

witnesses with consistent stories (Strange et al., 2014) implying that jurors’ over

reliance on consistency as a cue to honesty (evidence here) may also account

for scepticism of inconsistent evidence in real cases. However, examination of

this suggestion is prevented by the lack of video stimuli in much of the relevant

alibi research. This all implies that ambush alibis may be viewed as

synonymous with deception and rather than provide defendants with an

advantage in court, may actually benefit the prosecution (Culhane, et al., 2013).

Although they may arise out of a deliberate attempt to ambush the court,

genuine honest alibis that ambush the court can also occur. Despite a

widespread perception that memory is accurate (Valentine, 2008), copious

research illustrates that memory is reconstructed from incompletely encoded

information and influenced by schematic expectations (for example see

Osborne & Davies, 2014). Ridley (2013) and Brewer (1988) assert that greater

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONattention at the time of experiencing and encoding means that significant events

may be recalled more accurately. Although they are good at recalling which day

of the week a memorable event occurred, American college students frequently

cite the wrong week when asked for an alibi for a given time (Skowronski, Betz,

Thompson, & Shannon 1991). Similarly, when alibis are requested many

participants state where they usually are at the specified time, rather than where

they actually were if this deviates from their usual schema (Kurbat, Shevell, &

Rips, 1998; Leins & Charman, 2013). Due to the necessity of consulting

calendars and diaries to discover one’s own whereabouts, Kurbat et al. (1998)

termed this trend the calendar effect. These findings imply that innocent

suspects (for whom the time of the crime lacks significance until they become a

suspect) may be more susceptible to changing their alibi due to a reliance on

schemas and a lack of salience to their actions at the time of the crime. In fact,

Olson and Charman (2011) found that mistakes forced 36% of innocent mock

suspects to change their alibi just 48 hours after providing it, and Strange at al.

(2014) found that fewer than 50% of participants providing honest alibi stories

were consistent following a one-week delay. To consider all ambush alibis as

indicative of guilt is therefore inappropriate, as theoretically ambush alibis will

be more common amongst innocent defendants (Strange et al., 2014).

However, Culhane et al. (2013) found that, following a two day delay, 11.9% of

participants changed their deliberately false alibi story, compared to fewer than

4% of participants changing their truthful alibi suggesting that changes to alibis

may actually be more commonly associated with deception than honesty.

Dahl, Brimacombe, and Lindsay (2009) investigated the effect of alibi

evidence and eyewitness evidence timing within the police investigation setting.

Although examining the stage at which police interviewed the witnesses rather

than ambush strategies per se, their findings indicated that investigators are not

influenced more by eyewitness evidence than alibi witness evidence. Instead, a

strong alibi (colleague with corroborating receipts) was found to have an effect

on decision-making if it was received after eyewitness evidence. It was only

when the alibi presented was weak (best friend with no physical corroborating

evidence), and an eyewitness had positively identified the suspect, that alibi

evidence failed to influence mock-police evaluations of suspect guilt. These

findings clearly indicate the importance of timing and corroboration upon

evaluation of eyewitnesses and alibi witnesses within the low alibi-suspicion

investigation setting (Sommers & Douglass, 2007). In addition, researchers

have suggested that further research regarding alibi timing (alibi disclosed

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONduring initial investigations opposed to alibi disclosure during the trial) is

required (Mathews & Allison, 2010). It is therefore important that these

variables are assessed within the courtroom setting where general suspicion of

alibis is greater (Sommers & Douglass, 2007).

Although changes to alibis (Culhane et al., 2008; Culhane & Hosch, 2012;

Culhane et al., 2013), and the effect of alibi timing within cases, have been

assessed previously (Price & Dahl, 2014), the current research is the only study

to date examining whether ambush alibis influence juror decision-making. The

past relevant literature is unclear as to whether ambush alibis will be taken as

an indicator of inconsistency and deception, or unfairly benefit deceptive

defendants through prevention of police investigation of alibi veracity. Thus,

there is a need for empirical research regarding the effect of alibi disclosure

timing upon juror decision making.

Summary

Research illustrates that mock jurors assess the testimony of motivated and

unmotivated alibi witnesses differently. There is, however, no research

pertaining to evaluations of alibi witnesses and defendants in cases involving

ambush alibis, despite the evidence that ambush alibis may occur frequently.

The study reported here therefore examines the influence of timely and ambush

alibi evidence from motivated and unmotivated alibi witnesses upon juror

decision-making. In accordance with the theories of kin selection, reciprocal

altruism and lay perception that memory consistency is a cue to accuracy, it

was hypothesised that motivated alibi witnesses and ambush alibis would be

associated with more guilty verdicts than unmotivated alibi witnesses and timely

alibis. Additionally, it was anticipated that assessments of defendant reliability

and alibi witness reliability would be lower with ambush alibis and motivated

witnesses, than with unmotivated alibi witnesses and timely alibi evidence.

Method

Design

The study implemented a 2 x 2 between participants experimental design. Alibi

witness motivation (motivated, unmotivated) and alibi timing (timely, ambush)

were manipulated systematically in an assault case to create four experimental

conditions. A timely alibi occurred when defendants revealed their alibi within a

police interview, whereas an ambush alibi was only revealed in court. The

motivated witness was the defendant’s girlfriend, and the unmotivated alibi

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONwitness was the defendant’s neighbour. A fifth control condition contained no

alibi witness evidence. Juror verdicts (guilty, not guilty), verdict confidence, and

the perceived reliability of the defendant and the alibi witness formed the

dependant variables.

Participants

Participants were an opportunity sample of psychology students at university in

the North of England, as well as individuals from the community recruited

through a snowballing technique on an online social media site. The study was

hosted online and consisted of a series of linked webpages containing case

information and evidence questionnaires. A total of 180 participants were

evenly distributed between the five conditions took part in the research.

Participants all met the criteria for jury duty in England and Wales specified by

the Juries Act (1974); they were aged between 18 and 70 years, were resident

in the United Kingdom, the Channel Islands or the Isle of Man for a minimum of

five years since reaching 13 years of age, were on the electoral register, had

not served a prison or youth custody sentence within the previous ten years (or

of over five years duration at any time), and had no current or previous mental

health condition or mental illness. The sample was predominantly female with

48 males compared to 131 females (one participant did not record their sex).

The mean age of participants was 21.15 years (SD = 9.69), with participants

ranging from 18 to 63 years of age. The majority of participants were students

(74.4%).

Materials

The study materials were delivered sequentially in a series of linked webpages

with a separate URL associated with each condition. The first page outlined the

study procedure, requirements, data use and gained informed consent from

participants. The subsequent webpages contained the case indictment, trial

summary, and questions about the participants’ perceptions of the case.

The case was constructed so that there was sufficient evidence so that the

defendant could stand trial, but not so much evidence that his alibi (where

presented) would not be plausible and accurate. a qualified lawyer checked the

indictment and trial were checked to ensure the charge of grievous bodily harm

(GBH) brought against the defendant was appropriate to the injuries in the

scenario, and that sufficient evidence existed for a trial to reasonably occur.

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONThe prosecution case contained circumstantial evidence against the defendant

and an ambiguous timeline of events which provided the defendant with the

opportunity to commit the offence. Combined, this evidence produced a

tendency to guilty verdicts in the alibi witness absent control condition, which

allowed the relative effect of alibi witness testimony in the experimental

conditions to be assessed. As in previous mock jury research (Golding, et al.,

2000) the evidence was presented in the form of a detailed 4 page summary of

the case evidence.

Further webpages required participants to indicate their verdict (guilty, not

guilty) as well their confidence in this decision (rated from 0 [not at all confident]

to 100 [completely confident]). Other questions asked participants to rate the

reliability of the defendant and alibi witness (with scores ranging from 0 [not at

all reliable] to 100 [completely reliable]). The final webpage thanked and

debriefed participants as well as provided relevant sources of support and

contact details for the research team.

Procedure

The URL for each of the study conditions was placed on an online university

research participation database, as well as on social media. Each URL was

sequentially available until the necessary number of participants was recruited

to each condition. Upon clicking the URL, participants were taken to a secure

site containing the study information and materials. They then worked through

each page sequentially, reading information and providing responses where

appropriate.

Ethics

The study was conducted in accordance with the principles of the Code of

Human Research Ethics (British Psychological Society, 2006). This specific

study was assessed and approved by the ethics committees at Sheffield Hallam

University and Teesside University.

Results

Verdict

The majority of participants in each condition found the defendant guilty (see

Table 1) with the raw data suggesting that, compared to having no alibi witness,

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONa motivated alibi witness increases the frequency of guilty verdicts, whereas an

unmotivated alibi witness has no impact on perceptions of guilt. A 2 x 2 x 2

hierarchical loglinear analysis was conducted to assess the influence of alibi

witness (motivated, unmotivated) and alibi timing (timely, ambush) upon

participant verdict (guilty, not guilty). The main effect of verdict was significant;

Χ2(1) = 25.78, p < .001; signifying that significantly more participants voted

guilty (n = 102) than voted not guilty (n = 42). All other main effects and

interactions were not significant (all p > .05) indicating that the motivation and

timing of the alibi witness’s evidence had no impact upon participants’ verdicts.

Chi2 analyses comparing each of the experimental alibi conditions with the no

alibi condition were all non-significant (all p > .05) meaning there was no

significant association between condition and verdict.

Confidence in verdict

Across the whole sample, participants voting guilty (M = 73.27, SD = 14.59)

were on average more confident in their verdict choice, than those reaching a

not guilty verdict (M = 60.10, SD = 20.79; t(178) = 4.758, p < .001). Average

verdict confidence scores ranged from 62.47 (SD = 19.53) in the unmotivated

timely alibi condition to 73.94 (SD = 12.82) in the motivated timely alibi

condition. Table 1 illustrates that participants hearing no alibi, and those

hearing an alibi (either timely or ambush) from the defendant’s girlfriend were

more confident in their verdict, than participants hearing an alibi (either timely or

ambush) from the defendant’s neighbour. A one way ANOVA was conducted to

examine the effect of condition (unmotivated timely alibi, motivated timely alibi,

unmotivated ambush alibi, motivated ambush alibi, no alibi) upon verdict

confidence. Conducting a one way ANOVA rather than a factorial ANOVA

allowed for the no alibi condition to be included in this analysis as this condition

straddled both the alibi timing and alibi witness variables. Although the overall

ANOVA was significant; F(4, 175) = 2.54, p = .042, partial ƞ2 = .55; post hoc

Bonferroni tests between each condition did not support this difference (all p > .

05).

Insert Table 1 about here

Reliability of case evidence

Participants’ ratings of defendant reliability were generally low (less than 50% of

the available scale; see Table 2), with defendants rated least reliable when an

unmotivated witness supported their ambush alibis (M = 35.67, SD = 21.04) and

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONmost reliable when they had no supporting alibi witness (M = 41.25, SD =

22.37). A 2 x 2 ANOVA revealed no significant main effect of alibi timing or alibi

witness motivation on ratings of defendant reliability (F(1, 140) = .071, p = .790,

partial ƞ2 = .001 and F(1, 140) = .007, p = .931, ƞ2 = .000 respectively), and

there was no significant interaction between these variables, F(1, 140) = .331, p

= .566, partial ƞ2 = .002.

Insert Table 2 about here

Table 2 illustrates that both the motivated and unmotivated alibi witnesses were

rated as rather unreliable (M = 40.39, SD = 24.98) although variation was found

between conditions such that the unmotivated timely alibi witness was

perceived as the most reliable, and the motivated ambush alibi witness the least

reliable type of alibi witness (M = 56.75, SD = 23.17 and M = 33.33, SD = 25.27

respectively). A 2x2 ANOVA was conducted to examine the effect of alibi timing

(timely, ambush) and alibi witness motivation (motivated, unmotivated) upon

perceptions of alibi witness reliability. This revealed significant main effects of

alibi witness motivation; F(1, 140) = 12.92, p < .001, partial ƞ2= .084, and alibi

timing, F(1, 140) = 5.96, p = .016, partial ƞ2 = .041; as well as a significant

interaction between these variables; F(1, 140) = 5.75, p = .018, partial ƞ2 = .039.

Thus, a timely unmotivated alibi witness (M = 56.75, SD = 23.17) was perceived

as significantly more reliable than an ambush unmotivated alibi witness (M =

37.97, SD = 19.68). Similarly, a timely alibi from an unmotivated alibi witness

was rated significantly more reliable than a timely alibi from a motivated alibi

witness (M = 33.50, SD = 24.60). However, there was no significant difference

between the timely and ambush alibis provided by motivated alibi witnesses.

Discussion

The study revealed that both alibi witness motivation and alibi timing had an

effect upon mock juror perceptions of alibi witness reliability. Furthermore, alibi

witness evidence was rated as being rather unreliable (M = 40.39, SD = 24.98),

thus offering support for the alibi scepticism hypothesis (Olson & Wells, 2004).

However, defendants corroborated by an ‘unreliable’ alibi witness were not

viewed as less reliable than those supported by a more reliable witness.

Although prior research shows the police may believe that inaccurate alibis

arise from deliberate deception (Dysart & Strange, 2012), the current study did

not find support for this same belief amongst jurors as alibi witness motivation

and alibi timing did not have a significant impact on case verdicts. However,

due to the investigator bias (Masip, Alonso, Garrido, & Antón, 2005; Meissner &

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONKassin, 2002), the police officers sampled by Dysart and Strange might have

been inherently more suspicious of deception than the potential jurors in the

general population sampled in the current study. Instead, the current findings

support Olson and Charman’s (2011) assertion that jurors may interpret

inaccurate alibis as a sign of poor memory rather than deception. Qualitative

analysis of mock jury deliberations in cases with weak and/or changing alibis

would help to establish the accuracy of this assertion.

Alibi witness motivation

In accordance with previous research regarding the effect of alibi witness upon

alibi believability (Allison & Brimacombe, 2010), the present findings suggest

that although an unmotivated alibi witness has no impact upon a defendant’s

case, a motivated alibi witness may actually harm their defence. Hosch et al.

(2011) found that motivated alibi witnesses related by marriage to a defendant

(such as a sister-in-law) were perceived as less reliable than those with a social

relationship and more relievable than those with a biological relationship to the

defendant (Hosch, et al., 2011). In the current study, the girlfriend of the

defendant (motivated alibi witness) was viewed as a less reliable alibi witness

than the neighbour of the defendant (unmotivated alibi witness). Therefore, a

girlfriend alibi witness is viewed as more similar to a marriage or biological

related witness, than a socially related alibi witness. Thus, the data reflect the

suggestion that jurors perceive alibi witness evidence as an altruistic act

influenced by the degree of relatedness between a defendant and their alibi

witness (Hosch et al., 2011). These findings are in contrast to those of Marion

and Burke (2013) who observed that individuals lied to protect suspects who

appear innocent regardless of whether they like them. The relatively minor

crime (minor theft) and ability to lie through omission, rather than actively

construct a false story (Fawcett, 2012) could, however, account for Marion and

Burke’s differing findings.

Ambush alibis

As the unreliability of the ambush witness did not affect ratings of defendant

reliability or verdicts, there is no evidence that participants saw ambush alibis as

indicative of the alibi witness and defendant working together to deceive the

court. This finding is surprising given the widely held (but erroneous) belief that

inconsistency is a sign of deception (Mann, Vrij, & Bull, 2004; Sporer, Penrod,

Read, & Cutler, 1995), and that changes to testimony erode perceptions of

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONwitness confidence in court (Brewer & Burke, 2002), a factor previously

demonstrated to be associated with guilty verdicts (Cutler, Penrod, & Dexter,

1990). However, Berman and Cutler (1996) found that jurors rated novel

evidence in court (evidence not previously included in the investigation) as more

reliable than contradictory evidence in court, and contradictions between pre-

trial and in court evidence. The current study featured new evidence from a

new witness, rather than new/inconsistent evidence from an existing witness as

in Berman and Cutler’s (1996) and Brewer and Burke’s (2002) research. As the

decreased reliability of the ambush alibi witness (as indicated by participants)

was not sufficient to influence verdicts in the current study, it appears that a

contradictory alibi witness is perceived as less reliable than an alibi witness

whose testimony ambushes the court. This is an important finding because

truthful defendants often change their alibi stories (Olson & Charman, 2011).

The salience of witnessing a crime may make eyewitnesses less likely to

change their evidence than honest alibi witnesses who are unaware that their

actions at a particular time may later be of importance. Due to alibi witnesses’

more plausible susceptibility to the calendar effect (Brewer, 1988), changes to

an alibi should be viewed with less scepticism than changes to eyewitness

testimony (Olson & Charman, 2011). Although direct comparisons of

eyewitnesses and alibi witnesses were not possible, that all alibi witnesses were

not seen as entirely unreliable suggests that jurors may have some awareness

of the calendar effect. However, this did not stop participants from being more

sceptical of changing ambush alibis witness evidence than of consistent timely

alibi witness evidence. This suggests that an overestimation of the ease with

which an alibi can be supported (Strange et al., 2014; Turtle & Burke, 2001) is

the cause of this enhanced scepticism to changes to alibi evidence (Culhane,

2005). Furthermore, these findings imply that to promote fair evaluation of alibis

in court, judicial instruction on the difficulty of corroborating alibi stories and

providing jurors with experience of this task are required (Turtle & Burke, 2001).

Moreover, scepticism towards motivated alibi witnesses seems to negate the

effect of alibi timing in that motivated alibi witnesses were viewed as so

unreliable that ambush evidence was unable to further reduce juror reliability

ratings without that evidence being discounted altogether.

Verdicts

Although the current findings support the concept of a negative bias regarding

alibi witnesses, there was no effect of alibi timing or witness motivation upon

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONperceptions of defendant reliability or guilt. In contrast to previous research

(Culhane, 2005; Lindsay, Lim, Murando, & Cully, 1986) the presence of an alibi

witness had no effect on evaluations of the defendant or on case verdicts

compared to having no alibi corroborator. Thus, weak alibis do not affect jurors’

decision-making (Dahl et al., 2009). Shpurik and Meissner (2004) and Pozzulo,

Pettalia, Dempsey, and Gooden (2014) suggest that jurors only consider alibi

testimony when lacking other evidence against the defendant, an assertion

reinforced by the low reliability ratings of the alibi evidence in general in the

present study. This contradicts the results of similar studies which found higher

guilt ratings when a motivated alibi witness testified (Hosch et al., 2011).

Utilising a continuous measure of guilt, Hosch et al. found that a corroborating

alibi witness reduced belief in defendant guilt by 22%, but whether this

reduction translates into a not guilty verdict is dependent upon participant

formulations of the ‘reasonable doubt’ standard (Dhami, 2008) which have been

shown to vary widely (Horowitz, 1997). Horowitz demonstrated that reasonable

doubt varies from 60% to 90% certainty in guilt, meaning that a 22% reduction

may not be sufficient to convince participants of the defendant’s innocence.

The dichotomous verdict (guilty, not guilty) utilised in this study reflected the

real-world verdicts available to jurors but prevents examination of any more

subtle effects of the study variables upon levels of perceived guilt. As Olson

and Wells (2004) highlight, guilt estimates are not always sensitive enough to

measure perceptions of alibis, although further research with a more sensitive

measure of guilt help elucidate this new research area. Certainly, a belief that

the alibi witness was unreliable (and potentially that they were deceptive) did

not have a significant effect on evaluations of the defendant, suggesting that

any deception by the alibi witness is not seen as stemming from the defendant.

This is an interesting finding requiring further investigation through a qualitative

examination of mock juror deliberations over an alibi witness charged with

perjury.

Limitations

The online data collection used here may be seen as a limitation due to the

potential for different response patterns online and offline, and the lack of jury

deliberation, and summarised materials. However, while trial summaries have

limited ecological validity, they are appropriate in mock juror research

(Diamond, 1997). Moreover, prior juror decision-making research has used

online methodology (Evans & Schreiber, 2010). More specifically, no significant

Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATIONeffect of presentation modality (online or offline) has been found in other alibi

research (Fawcett, 2012). In general, the findings of psychological research

conducted using web technology do not differ substantially from those collected

using traditional pen and paper methodology (Gosling, Vazire, Srivastava, &

John, 2004). Furthermore, deliberations have not been used in the research

examining mock juror evaluations of alibi evidence (for example Burke & Turtle,

2004; Culhane & Hosch, 2004; Olson & Wells, 2004; Sommers & Douglass,

2007). This is due to extensive interviews with real jurors revealing that

deliberations play a modest role in determining verdicts (Bornstein, 1999;

Kalven & Zeisel, 1966; Meyers, Brashers, & Hanner, 2000).

Summary and conclusions

In summary, this study assessed whether alibi scepticism bias observed in

American mock juror studies (Culhane, et al., 2008; Olson & Wells, 2004) is

prevalent in the UK population. As alibi evidence was not rated as very reliable

the alibi scepticism hypothesis (Olson & Wells, 2004) and Turtle & Burke’s

(2001) assertion that people overestimate the ease of evidencing a genuine

alibi were supported.

More specifically the current study examined the specific impact of alibi timing

(timely, ambush) and alibi witness motivation (motivated, unmotivated) upon

juror decision-making. In support of prior research (Burke & Turtle, 2004;

Culhane, et al., 2008; Olson & Wells, 2004) motivated alibi witnesses were

perceived as significantly less reliable than unmotivated alibi witnesses. As

changes to testimony have been associated with deception and decreased

credibility (Berman & Cutler, 1996; Mann et al., 2004) it was anticipated, and

indeed found, that timely alibi witness evidence would be viewed as more

reliable than ambush alibi witness evidence. That defendant reliability and guilt

were not affected by type and timing of alibi witness corroboration, suggests

that a weak alibi alone is not sufficient to convince a jury of a defendant’s guilt.

Instead, jurors may see a weak or inconsistent alibi as reflecting genuine

memory failure or mistakes (Olson & Charman, 2011) rather than deliberate

deception. However, further research is required to explore the accuracy of this

suggestion. In summary, the findings imply that by allowing ambush alibi

evidence to be heard in the UK courts, judges do not appear to be providing

defendants with an unfair advantage.

17Running head: ALIBI TIMING AND ALIBI WITNESS MOTIVATION

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Table 1. Verdict and verdict confidence according to condition and decision reached


Conditiona Verdict Frequency (%) Verdict Confidence According to Condition and Decision Reached

Guilty Not Guilty Guilty Not Guilty

M SD M SD M SD

No alibi 63.89 36.1171.95

14.21 71.0914.61

73.46 13.90

Motivated timely alibi

72.22 27.7873.95

21.82 77.1911.74

65.50 12.12

Motivated ambush alibi

83.33 16.6771.42

19.91 75.3718.37

51.67 16.02

Unmotivated timely alibi

63.89 36.1162.47

19.54 68.0415.65

52.62 22.36

Unmotivated ambush alibi

63.89 36.1166.92

19.24 73.529.11

55.23 26.38


Note. an = 36


Table 2: Reliability of alibi witness evidence and defendant evidence by experimental condition

Condition

Evidence Type

Alibi Witness

Defendant

M

SD

M

SD

No alibi witness


N/A

N/A

41.25

22.37

Motivated timely alibi

33.50

24.60

36.33

23.74

Motivated ambush alibi

33.33

25.27


37.47

23.11

Unmotivated timely alibi

56.75

23.17

38.78

20.62

Unmotivated ambush alibi

37.97

19.68

35.67

21.04

Total


40.39

24.98

37.90

22.05Note. 0 = Not at all reliable, 100 = Completely reliable

the effect of evidence timing and witness motivation upon ... and ambush alibis d… · the effect...

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